Current high-k gate dielectric processes developed to meet the future transistor performance requirements in the 0.10 μm generation and beyond consist of generally two types: atomic layer chemical vapor deposition (ALCVD) and metal organic chemical vapor deposition (MOCVD). These processes permit formation of the necessary high-k film thickness and thickness uniformity.
However, MOCVD processes introduce undesired carbon (C)-containing impurities and the more mature ALCVD processes which use chlorine (Cl)-containing precursors create a sufficiently high chlorine content in the high-k films that degrades the electric performance of the devices using those high-k films.
For example, while an MOCVD process may use Zr(OC2H5)4 to form an ZrO2 film, carbon impurities (and hydrogen impurities) are formed in the high-k ZrO2 dielectric layer.
In another example, in an ALCVD process H2O is pulsed, then purged and then an HfCl4 precursor is pulsed then purged to form an HfO2 film. However, chlorine (Cl) impurities are formed in the high-k HfO2 film, especially proximate the interface between the HfO film and the substrate over which it is formed. ALCVD processes generally have a low process temperature of from about 250 to 350° C.
U.S. Pat. No. 6,271,094 B1 to Boyd et al. describes a method of making MOSFET with a high dielectric constant (k) gate insulator and minimum overlap capacitance.
U.S. Pat. No. 6,153,477 to Gardner et al. describes a process of forming an ultra-short transistor channel length using a gate dielectric having a relatively high dielectric constant.
U.S. Pat. No. 6,114,228 to Gardner et al. describes a method of making a semiconductor device with a composite gate dielectric layer and gate barrier layer.
U.S. Pat. No. 6,090,723 to Thakur et al. describes conditioning processes including annealing or high-k dielectrics.
U.S. Pat. No. 6,008,095 to Gardner et al. describes a process for the formation of isolation trenches with high-k gate dielectrics.